1. Field of the Invention
The present invention is in the field of manufacturing micro-optical, micro-mechanical or micro-fluidic components or elements. It more specifically relates to a method of manufacturing a replication-tool, sub-master or replica.
2. Description of Related Art
Micro-optical and micro-mechanical components are industrially mass-produced by various technologies, such as injection molding, roller hot embossing, flat-bed hot embossing, UV embossing (all these processes being replication processes) or lithography and etching processes. As an example, in the UV embossing process the surface topology of a master structure is duplicated into a thin film of a UV-curable epoxy resin on top of a substrate. In the case of micro-optics, the surface topology can be a refractive or a diffractive structure, or a combination of both. For that purpose, a tool (negative copy) is prepared from the master, which is then used to UV-emboss the epoxy resin. The substrate typically consists of a standard glass wafer, a high-precision machined refractive optical element or a wafer of opto-electronic components. The master can be a lithographically fabricated structure in fused silica or silicon, a laser or e-beam written microstructure or any other type of optical or mechanical microstructure. The component consisting of the substrate and epoxy layer is typically referred to as replica.
To achieve a cost effective mass production of replicated micro-optical components, a wafer-scale embossing process would be desirable. A ‘wafer’ in the meaning used in this text is a disc or a rectangular plate of any form stable, often transparent material. The diameter of the disk is typically between 5 cm and 40 cm, for example between 10 cm and 31 cm. Often it is cylindrical with a diameter of either 2, 4, 6, 8 or 12 inches. The wafer thickness is, for example, between 0.2 mm and 10 mm, typically between 0.4 mm and 6 mm. The wafer-scale replication allows the fabrication of several hundred identical structures with a single step, e.g. a single or double-sided UV-embossing process. The subsequent dicing step of the wafer then yields the individual micro-optical components. For an efficient wafer-scale replication technology a wafer-scale tool and consequently a wafer-scale master or submaster is required. However, in many cases it is either not possible or very costly to produce a master that covers a sufficiently large area (typically at least 4-6 inches). For instance, mastering techniques such as e-beam writing typically cover only a small area in the range of several square mm which is only the size of an individual micro-optical component. Therefore, a process is required that closes the gap between the size of the individual component to the full wafer scale.